In general, a sheet-handling device that carries out predetermined treatments is required to securely take out one sheet at a time from a bundle of stacked sheets. In compliance with the requirement a prior art sheet-handling device proposed up to now is provided with a take-out apparatus to prevent taking-out two sheets or more, i.e., a multi-sheet take-out prevention apparatus disclosed in Japanese Unexamined Patent Applications Tokkaihei 8-151135, Tokkaihei 9-110207, Tokkaihei 10-101239, Tokkaihei 10-250881.
Briefly, the sheet take-out apparatus disclosed in the Japanese Unexamined Patent Applications is provided with an air spout unit to spout air to a bundle of sheets, a take-out unit to suck a forward edge portion of a sheet and take it out from the bundle of sheets, and a depression unit disposed in the vicinity of the take-out unit to depress another forward edge portion of the sheets against the take-out unit. The sheet take-out apparatus particularly in Japanese Unexamined Patent Application Tokkaihei 10-101239 detects accompanied sheets or sheet conditions and feeds such detected information back to a controller in a take-out unit to achieve the optimum sheet take-out condition by controlling the following: depressing force of a voice coil motor, displacement of a movable sheet-feeding member of a sheet-feeding member, sucking force of a chamber block, or an actuator to adjust a position of an air nozzle.
As set forth above, the sheet take-out apparatus disclosed in the Japanese Unexamined Patent Applications proves to be difficult in taking out only one sheet at a time from the bundle of sheets primarily because the depression unit depresses the forward edge portion of the sheets against the take-out unit so that sheets at the take-out position are not always easily separate from each other. In addition, however, since sheets may be crushed immediately under a sheet take-out rotor in the take-out apparatus disclosed in Japanese Unexamined Patent Application Tokkaihei 10-101239, air is not supplied there. This leads to large friction among the sheets so that multi-sheet take-out troubles arise easily. In the case that changes in friction coefficients depend on sheet surface conditions, the sheet take-out apparatus is readily subject to their influence and its robustness becomes low.